1. Field of Invention
The present invention relates, in general, to an apparatus for damping a flywheel and, more particularly, to a flywheel damping apparatus, intended to improve noise, vibration and harshness (NVH) characteristics of an engine and vehicle drivetrain through a change in rigidity as well as the inertia of a flywheel.
2. Description of Related Art
Generally, the driving force is always unbalanced by the change in gas pressure of a piston in an internal combustion engine, thus generating a torsional exciting force in the engine. Thus, it is preferable for the transmission of the power of the engine to be as constant as possible while the engine is rotating.
In order to improve the NVH characteristics of a drivetrain, the flywheel serves to keep the rotating speed constant using inertia moment, and to lower the change in frequency of torsional vibrations transmitted from the engine, thus decreasing the NVH problem (driving, idle rattle, etc.) in the drivetrain.
Meanwhile, in recent years, the development and release of vehicles equipped with high-performance engines (to which a GDI, a turbocharger, a supercharger, a twin turbo, etc. has been applied) has become competitive. Particularly, in order to solve the problem of a luxury vehicle lacking in a starting feel (direct feel), a high torque engine is intended to be used in a low speed region.
However, as shown in FIG. 1, such an engine is problematic in that the NVH characteristics including rattles and booming noise are deteriorated, as the torsional exciting force of the engine is further increased. Particularly, as torsional vibrations increase in gear pairs of a gear step in a gearbox, shock and noise are further increased by the rattles.
In the prior art solutions to the above problems, as shown in FIG. 2, a mass body is mounted to a dual mass flywheel to perform relative rotation.
To be more specific, pairing mass bodies 20 are provided on a plurality of positions on both sides of a rotary flange 10, and each mass body 20 rotates relative to the rotary flange 10. Further, a locking pin 30 passes through the rotary flange 10, and the mass bodies 20 are secured, respectively, on both sides of the locking pin 30, so that the mass bodies 20 provided on both sides simultaneously rotate relative to the rotary flange 10.
Further, a pendulum hole H is formed in a lengthwise direction, in the direction in which the rotary flange 10 rotates, in at least one of the rotary flange 10 and the mass bodies 20 provided on both sides thereof and, and a pendulum roller 40 coupled to the rotary flange 10 is fitted into the pendulum hole H. As the mass body 20 performs relative rotation in a section of the pendulum hole H, the torsional vibrations transmitted from the engine are reduced.
However, considering only the rotational vibrations and the NVH characteristics of the vehicle drivetrain, the larger the inertial force of the flywheel is, the more advantageous they are. The inertial force of the flywheel tends to increase as a function of the weight and volume thereof; so that the size and weight of the flywheel should be increased if possible. However, the conventional mass-body installing structure is problematic in that, due to the lack of space, the inertia of the mass body, the length of the flywheel and of the mass body, and the distance from the center of the mass body to the axis of rotation of the flywheel, etc. are restricted, so that the possible increase in the vibration reducing effect that can be achieved using the conventional structure is limited.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.